FMDS0121 Fire Resistance Of Building Assemblies.pdf

January 2012
Page 1 of 50
FIRE RESISTANCE OF BUILDING ASSEMBLIES
Table of Contents
Page
1.0 SCOPE ................................................................................................................................................... 4
1.1 Changes ............................................................................................................................................ 4
2.0 THERMAL RESTRAINT ......................................................................................................................... 5
3.0 SPRAY-APPLIED FIRE PROTECTION COATINGS ............................................................................. 5
3.1 Mineral Fiber .................................................................................................................................... 5
3.2 Cementitious .................................................................................................................................... 5
3.3 Intumescent ..................................................................................................................................... 6
3.4 Application ....................................................................................................................................... 6
4.0 BEAMS ................................................................................................................................................... 6
4.1 Steel Beams .................................................................................................................................... 6
4.2 Concrete Beams .............................................................................................................................. 8
4.2.1 Reinforced Concrete Beams ................................................................................................. 8
4.2.2 Prestressed Concrete Beams ............................................................................................... 8
4.3 Timber and Glulam Beams ............................................................................................................... 8
5.0 COLUMNS .............................................................................................................................................. 9
5.1 Steel Columns .................................................................................................................................. 9
5.1.1 Spray-applied Protection ....................................................................................................... 9
5.1.2 Membrane Gypsum Board Protection ..................................................................................... 9
5.1.3 Concrete Encased Steel Columns ...................................................................................... 10
5.1.4 Concrete-Filled Hollow Steel ............................................................................................... 10
5.1.5 Plaster Protected Steel Columns ........................................................................................ 11
5.2 Concrete Columns ......................................................................................................................... 15
5.3 Cast Iron Columns ......................................................................................................................... 15
5.4 Timber and Glulam Columns .......................................................................................................... 16
6.0 WALLS AND PARTITIONS .................................................................................................................. 17
6.1 Masonry Walls ............................................................................................................................... 17
6.1.1 Masonry Walls with Gypsum Wallboard or Plaster Finishes ............................................... 20
6.1.2 Multiple-Wythe Masonry Walls ............................................................................................. 21
6.1.3 Crediting Core Fill for CMU .................................................................................................. 22
6.1.4 Masonry Cover for Reinforcing ............................................................................................ 22
6.2 Concrete Walls ............................................................................................................................... 22
6.2.1 Fire Endurance of Concrete Walls ........................................................................................ 22
6.2.2 Concrete Walls with Gypsum Wallboard or Plaster Finishes .............................................. 23
6.2.3 Concrete Cover .................................................................................................................... 23
6.2.4 Multiple-Wythe Concrete Walls ............................................................................................ 24
6.2.5 Precast Concrete Walls ........................................................................................................ 24
6.3 Solid Partitions ............................................................................................................................... 25
6.4 Hollow Partitions ............................................................................................................................ 27
6.5 Wall Joints .................................................................................................................................... 29
6.6 Autoclaved Aerated Concrete (AAC) Walls .................................................................................... 29
6.6.1 Reference Material and Design Specifications and Standards ........................................... 30
6.6.2 Fire Tests of AAC Walls ....................................................................................................... 30
6.6.3 Minimum Requirements for AAC Walls ................................................................................ 30
6.7 Fire-Rated Glazing ......................................................................................................................... 30
7.0 ROOF-CEILING ASSEMBLIES ........................................................................................................... 31
8.0 FLOOR-CEILING ASSEMBLIES ......................................................................................................... 32
9.0 FIRE STOPS ......................................................................................................................................... 39
FM Global
Property Loss Prevention Data Sheets 1-21
©2006-2012 Factory Mutual Insurance Company. All rights reserved. No part of this document may be reproduced,
stored in a retrieval system, or transmitted, in whole or in part, in any form or by any means, electronic, mechanical,
photocopying, recording, or otherwise, without written permission of Factory Mutual Insurance Company.

10.0 FRP REINFORCEMENT SYSTEMS ................................................................................................... 39
10.1 FRP Rebar .................................................................................................................................... 39
10.2 Externally-Applied FRP Reinforcement ........................................................................................ 40
11.0 HIGH STRENGTH CONCRETE (HSC) ............................................................................................... 40
11.1 Spalling of HSC ............................................................................................................................ 40
11.2 Fire-Exposed Strength of HSC ..................................................................................................... 40
12.0 FIRE ENDURANCE TESTS AND STANDARDS ............................................................................... 40
12.1 Fire Testing — General ............................................................................................................... 40
12.2 The ASTM E 119 Fire Tests of Building Construction and Materials .......................................... 41
12.2.1 Walls .................................................................................................................................. 42
12.2.2 Columns ............................................................................................................................ 43
12.2.3 Floors and Roofs ............................................................................................................... 43
12.2.4 Beams ................................................................................................................................ 44
12.2.5 Ceilings .............................................................................................................................. 44
12.3 Nonstandard tests ....................................................................................................................... 44
12.4 Other Fire Endurance Standards ................................................................................................ 44
12.4.1 Standard Time-Temperature Curve ................................................................................... 44
12.4.2 Sample Size ...................................................................................................................... 45
12.4.3 Acceptance ........................................................................................................................ 45
13.0 UNDERWRITERS LABORATORIES FIRE RESISTANCE DIRECTORY (ULFRD) .......................... 46
14.0 REFERENCES ................................................................................................................................... 46
APPENDIX A GLOSSARY OF TERMS ...................................................................................................... 47
APPENDIX B DOCUMENT REVISION HISTORY ...................................................................................... 49
List of Figures
Fig. 1. Heated perimeters for beams ............................................................................................................. 7
Fig. 2. Column profiles and heated perimeters, D. ...................................................................................... 10
Fig. 3. Section view of proprietary fire-rated joint detail. ............................................................................. 29
Fig. 4. ASTM E 119 standard time-temperature curve ................................................................................ 41
Fig. 5. Comparison of ASTM E 119 time-temperature curve with a hydrocarbon pool fire
time-temperature curve .................................................................................................................... 42
Fig. 6. Time-temperature curves used in various countries ........................................................................ 45
List of Tables
Table 1. Fire Resistance of Plaster Protected Steel Columns .................................................................... 12
Table 1. Fire Resistance of Plaster Protected Steel Columns (cont’d.) ...................................................... 13
Table 2. Fire Resistance of Protected Steel Columns ................................................................................. 14
Table 3. Minimum Concrete Cover for Reinforced Concrete Columns ....................................................... 15
Table 4: Minimum Column Dimension for Reinforced Concrete Columns .................................................. 15
Table 5. Fire Resistance of Cast-Iron Columns ............................................................................................ 16
Table 6. Masonry Walls ................................................................................................................................ 18
Table 6.1 Equivalent Thickness and Minimum Face Shell Thickness of 2-Core Concrete Masonry Units* . 19
Table 6.2 Equivalent Thickness and Minimum Face Shell Thickness of 3-Core Concrete Masonry Units* . 19
Table 6.3 Fire Endurance Assigned to Finish Materials on the Fire- Exposed Side of Masonry Wall ....... 20
Table 6.4 Factors for Finish Thickness on Non-Fire-Exposed Side of Masonry Wall .................................. 21
Table 6.5 Fire Endurance of Double-Wythe Masonry Wall .......................................................................... 22
Table 7. Fire Endurance and Minimum Thickness of Concrete Walls ......................................................... 23
Table 7.1 Factors for Finish Thickness on Non-Fire-Exposed Side of Concrete Wall ................................. 23
Table 7.2 Minimum Concrete Cover of Steel Reinforcement for Fire Resistance of Concrete Walls ........ 24
Table 8. Solid Nonbearing Patitions ............................................................................................................. 25
Table 8. Solid Nonbearing Partitions (cont’d.) ............................................................................................. 26
Table 9. Hollow Nonbearing Partitions ......................................................................................................... 27
Table 10. Stud Walls and Partitions, Bearing and Nonbearing 3
................................................................ 28
Table 11. Fire Resistance of Plank-on-Timber Floors .................................................................................. 32
Table 12. Fire Resistance of Wood-Joisted Floors ...................................................................................... 33
Table 13. Fire Resistance of Steel-Joisted Floors ....................................................................................... 34
Table 14. Fire Resistance of Reinforced Concrete Floors ........................................................................... 35
Table 15. Fire Resistance of Prestressed Concrete Units ........................................................................... 36
1-21 Fire Resistance of Building Assemblies
Page 2 FM Global Property Loss Prevention Data Sheets
©2006-2012 Factory Mutual Insurance Company. All rights reserved.

Table 16. Fire Resistance of Composite Floors ........................................................................................... 37
Table 16. Fire Resistance of Composite Floors (cont’d.) ............................................................................ 38
Fire Resistance of Building Assemblies 1-21
FM Global Property Loss Prevention Data Sheets Page 3

1.0 SCOPE
This document provides guidelines for estimating the fire endurance of existing building components and
assemblies and information from which assemblies having a given fire endurance can be constructed. Fire
endurance is the length of time during which a component or assembly continues to exhibit fire resistance.
Fire resistance is a property of a component or assembly and is associated with either the ability to confine
fire to its compartment of origin or to perform a given structural function.
Recommendations for fire endurance ratings can be found in FM Global Property Loss Prevention Data
Sheets 1-3, 1-20, 1-22, the 7-series, and 8-series data sheets, and applicable building codes. The ratings
given are in accordance with American Society for Testing and Materials (ASTM) E 119 (NFPA 251, UL 263),
ASTM E 814 or acceptable modifications thereof. However, for a discussion of time-temperature curves used
by other countries, see Section 12.
Unless noted as specific to high-strength concrete, the concrete-related recommendations in this data sheet
are intended to apply to normal-strength concrete. Refer to Appendix A for definitions of normal- and
high-strength concrete, and refer to Section 11 for recommendations specific to high-strength concrete.
The types of building materials and assemblies included in this data sheet are:
1. Walls subject to standard fire exposure (ASTM E 119) from one side and a hose stream, where applicable.
(Note that a different rating may result for either side if the wall is not symmetrical. See later discussion.)
2. Columns subject to standard fire exposure from all sides.
3. Floor-ceiling or roof-ceiling assemblies subject to standard fire exposure from below.
4. Fire-stop materials for sealing around electrical and mechanical service penetrations through walls,
ceilings and floors.
Some items not included are:
1. Fire doors. See the Approval Guide, a publication of FM Approvals.
2. Protection of structural steel for storage areas. See the applicable 8-series storage Loss Prevention
Data Sheets and the Approval Guide.
3. Undercoating that allows a Class 2 insulated steel deck roof to meet the fire hazard requirements of
Class 1 roof. See Loss Prevention Data Sheet 1-28R/1-29R, Roof Systems and the Approval Guide.
1.1 Changes
January 2012. The following changes were done for this revision:
1. Added recommendations for Autoclaved Aerated Concrete (AAC).
2. Added recommendations for double-wythe concrete masonry unit (CMU) walls, and CMU and concrete
walls with fire-resistant finish materials such as plaster and gypsum board, with example problems.
3. Added recommendations for CMU cavity walls and hollow partition walls that contain foam plastic insulation.
4. Added recommendations and guidance for CMU % solid, face shell thickness, aggregate-based densities,
and the fire-resistance benefits of grout-filled CMU.
5. Added recommendations to address high strength concrete (HSC) spalling and fire-exposed strength.
6. Added and revised recommendations for precast/prestressed (pc/ps) concrete and cast-in-place post-
tensioned (pt) concrete - and new guidance for identifying the various types of concrete.
7. Added recommendations for fiber-reinforced polymer (FRP) rebar and externally-applied FRP reinforcing.
8. Added and revised recommendations regarding concrete cover for fire walls.
9. Added recommendations for heavy timber and glulam framing.
10. Added recommendations and guidance on ISO 834 and BS 476 time-temperature curves and fire tests.
11. Added background structural steel columns tested per the ASTM E119 fire test standard and the
difference between the loaded and unloaded (limiting steel temperature) test options.

12. Added and revised guidance on fire-resistance rated glass and glazing.
13. Added guidance on firestopping and the TFM rating in the FM Approval Guide.
14. Added an extensive glossary of terms.
2.0 THERMAL RESTRAINT
In fire tests of building elements, the element is considered restrained if the forces of expansion are resisted
by forces external to the element. An element is considered unrestrained if it is free to expand and rotate
at its supports.
In general, restrained elements or assemblies are capable of achieving greater fire endurance ratings than
equivalent unrestrained elements or assemblies. This is due in large part to the different failure criteria for
restrained and unrestrained elements in the various fire endurance tests. Consider an assembly that employs
an unrestrained steel beam. According to ASTM E 119, test failure is determined to have occurred when
either the average temperature in the steel beam has reached 1100°F (593°C) or the maximum temperature
at any point in the steel beam has reached 1300°F (704°C). The elapsed time at which this occurs is the
fire endurance rating.
For restrained assemblies, the same limiting temperatures are allowed at half the rated time or a minimum
of 1 hour. The fire endurance rating is then the time at which the ultimate load capacity is exceeded or twice
the time at which the temperature limits are reached, whichever is lower.
3.0 SPRAY-APPLIED FIRE PROTECTION COATINGS
A variety of coverings and coatings are available to limit the temperature of structural members in a fire.
The two most basic categories of fire protection are membrane protection and direct application. Membrane
protection refers to products that are used in such a way that they are independently supported from the
surface they are protecting. This group includes batts, blankets and board stock. An example is boxing in with
board stock materials like gypsum board. Direct applied protection refers to products that are applied directly
to the substrate they are to protect. They generally are adhesively attached to the substrate. These coatings
can be either troweled-on, formed and poured or spray-applied. An example is encasement in concrete,
plaster, or gypsum.
A large variety of spray-applied coatings are available. However, they can generally be classified into three
types:
• Mineral fiber
• Cementitious
• Intumescent
3.1 Mineral Fiber
Mineral fiber is molten volcanic rock that is spun into fine threads. The fibers are applied to the substrate
by spraying with water. Tamping and the use of adhesives and sealers is usually optional.
Spray-applied mineral fiber fireproofing can be susceptible to damage. It can be removed manually or by
accidental impact.
3.2 Cementitious
Cementitious coatings use cement and some type of aggregate. The type of cement (portland, gypsum, etc.)
and the type of aggregate will determine the density and impact resistance of the material. It is cost-effective
to use very lightweight aggregates since the material does not require significant compressive strength as
does normal concrete. Therefore, the aggregates used are typically expanded minerals such as perlite and
vermiculite or expanded plastics such as polystyrene.
3.3 Intumescent
Intumescent materials expand when exposed to the heat of a fire and form an insulating layer. Intumescents
can be further classified as either paints or mastics.

3.4 Application
Prior to application of spray-applied fire resistive coatings, the substrate surface must be free of dirt, grease,
oil and loose mill scale. Mill scale (dark gray color) need not be totally removed. Blast cleaning of the surfaces,
although the most effective, is costly and normally not justified. However, it may be required for some
proprietary systems. If this is the case, it would be indicated in the listing.
Cleaning with hand tools such as wire brushes is generally adequate. Priming or pre-painting is not normally
required either. In fact, use of an incompatible paint may result in inadequate adhesion of the spray-applied
fire protection to the surface.
4.0 BEAMS
4.1 Steel Beams
Steel beams may be tested and rated as part of an assembly or as individual members (beam-only tests).
The difference can be significant in certain cases. In the beam-only tests, a more generic type roof/ceiling is
used. The ratings developed from the assembly tests will be for specific roof/ceiling constructions. When
steel beams of a different size are substituted for the beam in the listed design, the following formula can
be used to determine the required thickness of spray-applied fire protection for the substitute beam:
English units
h2 = h1[(W1/D1)+0.6]/[(W2/D2)+0.6] (Eq. 1)
SI units
h2 = h1[(W1/D1)+0.036]/[(W2/D2)+0.036] (Eq. 1)
provided:
1. W/D ≥ 0.37 (English units) or W/D ≥ 0.022 (SI units)
2. h ≥ 3⁄8 in. (9.5 mm)
3. The unrestrained beam rating ≥ 1 hr.
where:
h = thickness of sprayed-on fireproofing material, inches (mm)
D = heated perimeter of the steel beam, inches (mm) (See Fig. 1)
W = weight of the steel beam, lb/ft (kg/m)
Subscript 1 refers to the design beam and coating thickness
Subscript 2 refers to the substitute beam and coating thickness

4.2 Concrete Beams
4.2.1 Reinforced Concrete Beams
The concrete cover for an individual steel reinforcing bar (rebar) is the minimum thickness of concrete between
the surface of the rebar and the fire exposed surface of the beam. For beams in which several rebars are
used, the cover is the average of the minimum cover of the individual bar. For corner bars (i.e., bars equal
distance from the bottom and side), the minimum cover used in calculating the average should be half the
actual minimum cover for the individual bar. The cover of an individual bar should not be less than 3⁄4 in. (19
mm).
4.2.2 Prestressed Concrete Beams
The concrete cover for an individual tendon is the minimum thickness of concrete between the surface of
the tendon and the fire exposed surface of the beam. For beams in which several tendons are used, the cover
is the average of the minimum cover of the individual tendons. For corner tendons (i.e., tendons equal
distance from the bottom and side), the minimum cover used in calculating the average should be half the
actual minimum for the individual tendon. The cover of an individual tendon should not be less than 1 in. (25
mm).
When computing the cross-sectional area of a beam cast monolithically with the supported slab, the
cross-sectional area of a section of slab equal to 3 times the average width of the beam can be included.
4.3 Timber and Glulam Beams
This section applies to heavy timber construction consisting of either solid timber or glued-laminated (glulam)
beams.
All dimensions noted in this section are actual dimension, not nominal dimensions.
Heavy timber can provide some fire endurance without protective coatings or sheathing due to the insulating
effect the charred wood provides to the underlying wood.
Fig. 1. Heated perimeters for beams

4.3.1 Minimum Beam Size
The minimum beam size is 5.5 in. (140 mm) wide x 9.5 in. (240 mm) deep.
4.3.2 Credited fire endurance of timber and glulam beams is limited to 60 minutes.
4.3.3 Only use 3-sided fire exposure to determine the fire endurance when the top side (width) of the beam
has the same or better protection as noted for the timber connector and fasteners in Section 4.3.6.
4.3.4 Fire Endurance of Unprotected Timber Beams
Notation:
b = beam width (in. [mm])
d = beam depth (in. [mm])
Timber Beam Fire-Exposed on 4 Sides:
Fire Endurance (min.) = 3.3(b) [4-2(b/d)] ≤ 60 min. (English units) (Eq. 2)
Fire Endurance (min.) = 0.13(b) [4-2(b/d)] ≤ 60 min. (Metric [SI] units) (Eq. 2)
For example:
When b = 7.5 in., and d = 11.5 in.,
Fire Endurance = 3.3(7.5) [4-2(7.5/11.5)] = 67 min., but use 60 min.
Timber Beam Fire-Exposed on 3 Sides:
Fire Endurance (min.) = 3.3(b) [4-(b/d)] ≤ 60 min. (English units) (Eq. 3)
Fire Endurance (min.) = 0.13(b) [4-(b/d)] ≤ 60 min. (Metric [SI] units) (Eq. 3)
4.3.5 Fire Endurance of Unprotected Glulam Beams
Up to 1-hour fire endurance can be achieved by replacing at least one core lamination, which is at least
1.5-in. (38 mm) thick, with a tension lamination of equal to greater thickness in the tension zones of the glulam
beam. Alternatively, an additional tension lamination of at least 1.5-in. (38 mm) can be added to the tension
zones of the beam.
4.3.6 Connectors and Fasteners for Timber and Glulam Beams
Provide not less than 5/8-inch (16 mm) Type X gypsum board, 1.5-inch (38 mm) thick wood, or a material
verified to be acceptable by fire-testing, to cover and protect connectors and fasteners for fire endurance
ratings up to 1 hour.
5.0 COLUMNS
The fire endurance rating generally increases as the thickness of the steel increases for a steel column and
as the cross-sectional area increases for a reinforced concrete column. However, in the case of reinforced
concrete, the fire endurance is also dependent on the thickness of the concrete cover over the reinforcing
steel.
5.1 Steel Columns
5.1.1 Spray-applied Protection
The fire endurance of steel columns protected by sprayed-on mineral fiber or cementitious fire proofing can
be calculated using the formula:
English units
R = [C1(W/D)+C2]h (Eq. 4)
SI units
R = [C1(17W/D)+C2]h/25.4 (Eq. 4)
where:

R = fire endurance, minutes
h = thickness of sprayed-on fireproofing material, inches (mm)
D = heated perimeter of the steel column, inches (mm) (See Fig. 2.)
W = weight of the steel column, lb/ft (kg/m)
C1 & C2 = material constants dependent on the type of fire proofing material.
For cementitious material, C1 = 69 and C2 = 31
For mineral fiber material, C1 = 63 and C2 = 42
Refer to FM Global Data Sheet 1-1, Firesafe Building Construction and Materials, for additional guidance.
5.1.2 Membrane Gypsum Board Protection
The fire endurance of steel columns boxed with gypsum wallboard can be calculated using the formulas:
English units
R = 2.17[h(W’/D)/2]0.75
(Eq. 5)
SI units
R = 1.6[h(W’/D)/2]0.75
(Eq. 5)
where:
R = fire endurance, hours
h = thickness of gypsum wallboard, inches (mm)
D = heated perimeter of the steel column, inches (mm) (See Fig. 2.)
W = weight of the steel column, lb/ft (kg/m)
W’= weight of the steel column and gypsum wall board protection, lb/ft (kg/m)
English units
W’=W+[50(hD)/144] (Eq. 6)
SI units
W’=W+0.0008hD (Eq. 6)
Fig. 2. Column profiles and heated perimeters, D.

5.1.3 Concrete Encased Steel Columns
For concrete-encased steel columns, the fire-endurance ratings are affected by the thickness of the concrete
protection and by the type of aggregates used in the concrete. Concrete containing limestone and dolomitic
gravel aggregates has greater fire resistance than concrete containing siliceous aggregates. For protected
steel columns, a rating of more than 4 hr is seldom required, and a concrete thickness of less than 2 in.
(51 mm) is seldom practical.
5.1.4 Concrete-Filled Hollow Steel
Determine the fire endurance rating of hollow steel columns (e.g., pipe and structural tubing) with their core
filled with unreinforced concrete should be determined in accordance with the following:
English units
R = [0.58a(f’c+2.9)/(KL-3.28)]D2
(D/C)1/2
(Eq. 7)
SI units
R = [a(f’c+20)/(KL-1000)]D2
(D/C)1/2
(Eq. 7)
Where:
R = fire endurance rating, hours
a = 0.07 for circular columns filled with siliceous aggregate concrete
0.08 for circular columns filled with carbonate aggregate concrete
0.06 for rectangular columns filled with siliceous aggregate concrete
0.07 for rectangular columns filled with carbonate aggregate concrete
f’c = specified 28-day concrete compressive strength, ksi (MPa)
KL = column effective length, ft (m)
L = actual length, ft (m)
K = effective length factor. If unknown, assume 1.0 for columns supported at both ends and 2.0 for cantilevered
columns.
D = outside diameter for circular columns and least outside dimension for rectangular columns, in. (mm)
C = compressive force due to unfactored dead load and live load, kips (KN)
1 kip = 1000 lb
The application of these equations is limited as follows:
1. The required fire endurance rating time should be ≤ 2 hours.
2. The specified concrete compressive strength should be ≥ 2.9 ksi (20 MPa) and ≤ 5.8 ksi (40 MPa).
3. The column effective length should be at least 6.5 ft (2.0 m) and no greater than 13.0 ft (4.0 m).
4. D should be at least 5.5 in. (140 mm) and no greater than 12 in. (305 mm) for rectangular columns or
16 in. (410 mm) for circular columns.
5. C should not exceed the design strength of the concrete core.
5.1.5 Plaster Protected Steel Columns
The ratings of Designs A to F in Table 1 were based on a W10 x 49 columns (10 x 10 in., [254 x 254 mm];
weighing 49 lb/ft or 73 kg/m). One test was repeated with a W6 x 20 (6 x 6 in., [152 x 152 mm]; weighing
20 lb/ft [30 kg/m]). The W6 x 20 column failed 10% sooner than the W10 x 49. The column Designs A to F in
the test series used to prepare Table 1 were tested to failure. Failure occurred more than 10% later than
the assigned endurance for ratings up to 3 hour, and at least 6% above the assigned endurance for the 4-hr
ratings. By relying on the overrun in the tests, Designs A to F in Table 1 can be used for all columns
with a minimum flange thickness of 0.36 in. (9 mm).
The minimum thickness of protecting material (as shown on the sketches in Tables 1 and 2) is measured
from the lath outward for metal lath and plaster types of protection, and from the face of the column outward
for other types of protection. The ratings for the protected steel columns in Table 2 should not be used with
net areas of metal and protecting material less than those given in the table.
The following references apply to the sketches in these tables and are applicable to Designs A to F in Table 1.

1. Metal or rib lath. No. 24 USS gage (0.58 mm). Unless otherwise noted, 3.4 lb/sq yd (1.8 kg/sq m).
a. Metal lath. A self-furring, 3⁄8-in. (10 mm) expanded diamond-mesh lath. These metal-lath sections
should be lapped 1 in. (25 mm) and tied 6 in. (152 mm) on centers.
b. Rib lath. A small-mesh metal lath with 3⁄8-in. (10 mm) deep, heavy reinforcing ribs spaced approximately
4 in. (102 mm) on centers. Sections of this lath should be butted and held tightly against the column with
No. 24 gage (0.58 mm), 1⁄2-in. (13 mm) wide bands.
2. Steel corner bead. To provide desirable plaster thickness on face of lath and protection for corners.
3. Metal lath spacer. To support metal lath 11⁄4 in. (32 mm) from column.
4. Furring channel. 3⁄4-in. (19 mm) cold-rolled steel channel at about 2 ft (0.6 m) vertical spacings. Web
of channel horizontal; bent around columns with ends lapped at least 3 in. (76 mm) and double tied.
5. Gypsum wall board. 1⁄2-in. (13 mm) thick.
6. Wire. No. 18 gage (1.21 mm) soft annealed galvanized wire fastened around the gypsum board 18 in.
(0.46 m) on center vertically.
7. Wire mesh. 1 in. (25 mm) mesh, No. 17 gage (1.47 mm) over scratch coat.
8. Perforated gypsum lath. 3⁄8-in. (10 mm) lath applied in one or two layers.
9. Plaster. For fire protection.
a. Perlite plaster. Scratch (base) coat 2 ft3
(0.057 m3
) and brown finish coat 3 ft3
(0.085 m3
) to 100 lb
(45 kg) of fibered gypsum. Finish coat 1⁄16-in. (1.59 mm) thick.
b. Vermiculite plaster. Scratch (base) coat 2 ft3
(0.057 m3
) and brown (finish) coat 3 ft3
(0.085 m3
) to
100 lb (45 kg) of fibered gypsum. Finish coat 1⁄16-in. (1.59 mm) thick.
c. Fireproofing cement. A proprietary premixed cement, mixed with water to form a stiff plastic mix for
plastering application.
d. Portland cement plaster. Scratch (base) coat 2:1:8 and brown (finish) coat 2:1:10 (ratios are portland
cement:lime:sand).
e. Gypsum sanded plaster. 1 part gypsum to 3 parts sand.

Table 1. Fire Resistance of Plaster Protected Steel Columns
Type of Construction
Minimum
Thickness t,
in. (mm)
Protecting Material
Fire Resistance,
hr
Plaster, Design A 13⁄4 (44) Vermiculite plaster 4
13⁄4 (44) Perlite plaster 4
13⁄8 (35) Vermiculite plaster 3
13⁄4 (44) Portland cement plaster 3
1 (25) Perlite plaster 2
1 (25) Vermiculite plaster 2
1 (25) Portland cement plaster 1
Plaster, Design B
11⁄2 (38) Vermiculite plaster 4
1 (25) Vermiculite plaster 3
Plaster, Design C
1 (25) Portland cement plaster 1
3⁄4 (19) Sanded gypsum plaster 1

Table 1. Fire Resistance of Plaster Protected Steel Columns (cont’d.)
Minimum
Thickness t,
in. (mm)
Protecting Material
Fire Resistance,
hr
Plaster, Design D One Layer Gypsum Wallboard
25⁄8 (67)
21⁄8 in. (54 mm) perlite plaster over
1⁄2 in. (13 mm) gypsum board
4
2 (51) Two 3⁄4 in. (19 mm) coats perlite 3
Multiple Layers Gypsum Wallboard
21⁄2 (64) Two 3⁄4 in. (19 mm) coats perlite plaster 4
21⁄2 (64)
Two 3⁄4 in. (19 mm) coats vermiculite
plaster
4
2 (51) 1 in. (25 mm) perlite plaster 3
2 (51) 1 in. (25 mm) vermiculite plaster 3
1 (25)
2 layers gypsum wallboard with no
plaster
1
11⁄2 (38)
plaster
11⁄2
2 (51)
plaster
2
Plaster, Design E Two Layers Perforated Gypsum Lath
2 (51)
2 coats vermiculite plaster, 5⁄8 in.
(16 mm) scratch coat and 5⁄8 in.
(16 mm) brown coat
3
One Layer Perforated Gypsum Lath
13⁄8 (35) 1 in. (25 mm) perlite plaster 2
13⁄8 (35) 1 in. (25 mm) vermiculite plaster 2
1 (25) 5⁄8 in. (16 mm) layer gypsum board 11⁄2
Plaster, Design F
11⁄2 (38)
Perlite plaster (Fill space between
metal lath and flange of steel column)
4

Table 2. Fire Resistance of Protected Steel Columns
Minimum
Thickness t,
in.
(mm)
Protecting Material
Minimum
Area1
,
in.2
(cm2
)
Fire
Resistance,
hr
Concrete (completely encased) 2
(51)
Concrete with calcareous aggregate
100
(645)
4
2
(51)
Concrete with siliceous aggregate
100
(645)
3
3
(76)
100
(645)
4
2
(51)
144
(929)
4
Concrete (re-entrant spaces filled)
Note: Any type steel section with metal thickness
at least 0.20 in. (5 mm)
Re-entrant spaced filled with a 1:6 or
1:2:4 concrete mixture, all
aggregates, tied with vertical &
horizontal ties.
60
(387)
3⁄4
35
(226)
1⁄2
Fireproofing (completely encased) 11⁄2
(38)
Vermiculite 2
17⁄8
(48)
Vermiculite 3
21⁄8
(54)
Sprayed gypsum plaster 3
21⁄2
(64)
Sprayed gypsum plaster 4
Brick or hollow tile 4
(102)
Common brick
270
(1742)
7
2
(51)
Common brick
180
(1161)
13⁄4
2-3-4
(51-76-102)
Hollow tile (clay or shale) with wire
mesh in horizontal joints, re-entrant
space filled with concrete
225
(1452)
4
220
(1419)
31⁄2
180
(1161)
3
145
(935)
21⁄2
110
(710)
2
80
(516)
11⁄2
Note: 1. Minimum area is area of steel and protecting material. Deduct voids in hollow tile.

5.2 Concrete Columns
Refer to Table 3 and Table 4 for minimum concrete cover, and minimum dimensions of reinforced concrete
columns of different aggregate types, for fire endurance ratings of 1 to 4 hours. The minimum dimensions
of Table 4 do not apply to columns built into walls (i.e., pilasters) provided that:
1. The fire endurance of the wall is equal to or greater than the required fire endurance of the column;
2. Openings in the wall are protected; and
3. The main longitudinal reinforcement in the column has the minimum cover specified in Table 3.
Table 3. Minimum Concrete Cover for Reinforced Concrete Columns
Fire Endurance (Hours)
Concrete Cover
(in.) (mm)
1 1.0 25
1.5 1.5 38
2 2.0 51
3 2.0 51
4 2.0 51
Notes:
1) Concrete cover is the clear cover to the main longitudinal reinforcing.
2) Concrete cover shown is for conventional reinforcement (rebar), regardless of aggregate type.
3) For prestressed (strand) or post-tensioned (tendon) columns, provide the same concrete cover as is recommended for walls in Table
7.2 for the needed fire endurance, but not less than the concrete cover in this table.
Table 4: Minimum Column Dimension for Reinforced Concrete Columns
Fire Endurance
(Hours)
Minimum Column Dimension*
Aggregate Type
Siliceous Carbonate Sand- Lightweight
(in.) (mm) (in.) (mm) (in.) (mm)
1 8 203 8 203 8 203
1.5 9 229 9 229 8.5 216
2 10 254 10 254 9 229
3 12 305 11 279 10.5 267
4 14 356 12 305 12 305
*Minimum column dimension is the minimum diameter for round columns, and the lesser of the cross-sectional dimensions for rectangular
columns.
5.3 Cast Iron Columns
Refer to Table 5 for the fire endurance rating of cast iron columns. Cast iron columns with concrete fill in
their core but no exterior fire protection coating will have a fire endurance rating of 1/2 hr or less, and unfilled
and unprotected cast iron columns will have a fire endurance rating of 20 minutes or less, in theory. However,
exposed cast iron columns may shatter if subjected to water spray after fire exposure. Therefore, for any
reliable fire endurance rating, cast iron columns should be encased in fire resistant material.
The ratings for the columns in Table 5 should not be used with net areas of metal and protecting material
less than those given in the table.

Table 5. Fire Resistance of Cast-Iron Columns
Minimum
Thickness t,
in. (mm)
Protecting Material
Minimum
Area1
in.2
(cm2
)
Fire Rating,
hr
Encased with concrete 2
(51)
Concrete 1:6 or 1:7 mix tied
with not less than AWG No. 5
(4.6 mm) wire on 8 in.
(203 mm) pitch
70
(452)
2
No exterior protection2
0.60
(15)
Interior filled with concrete 35
(226)
1⁄2
0.30
(8)
Interior filled with concrete 55
(355)
25 minutes
0.60
(15)
Unfilled 12
(77)
20 minutes
Notes:
1. Minimum area refers to the area of solid material excluding inside the column if unfilled.
2. Cast iron columns with no exterior protection will have a useful fire resistance rating of 1⁄2 hr or less. If exposed to fire and then a hose
stream, cast iron is likely to shatter from thermal shock.
5.4 Timber and Glulam Columns
This section applies to heavy timber construction consisting of either solid timber or glued-laminated (glulam)
columns.
All dimensions noted in this section are actual dimension, not nominal dimensions.
5.4.1 Minimum Column Size 7.5 in. (190 mm) wide x 7.5 in. (190 mm) deep
5.4.2 Credited fire endurance of timber and glulam columns is limited to 60 minutes.
5.4.3 Only use 3-sided fire exposure to determine the fire endurance when one side of the column has the
same or better protection as noted for the timber connector and fasteners in Section 5.4.5.
5.4.4 Fire Endurance of Unprotected Timber and Glulam Columns
Notation:
b = lesser column dimension (in. [mm])
d = greater column dimension (in. [mm])
Timber or Glulam Column Fire Exposed on 4 Sides:
Fire Endurance (min.) = 3.3(b) [3-(b/d)] ≤ 60 min. (English units) (Eq. 8)
Fire Endurance (min.) = 0.13(b) {3-(b/d)] ≤ 60 min. (Metric [SI] units) (Eq. 8)
Timber or Glulam Column Fire Exposed on 3 Sides:
Fire Endurance (min.) = 3.3(b) [3-(b/2d)] ≤ 60 min. (English units) (Eg. 9)
Fire Endurance (min.) = 0.13(b) [3-(b/2d)] ≤ 60 min. (Metric [SI] units) (Eq. 9)
5.4.5 Connectors and Fasteners
Provide not less than 5/8-inch (16 mm) Type X gypsum board, 1.5-inch (38 mm) thick wood, or a material
verified to be acceptable by fire-testing, to cover and protect connectors and fasteners for fire endurance
ratings up to 1 hour.
6.0 WALLS AND PARTITIONS
Tables 6 through 10 give ratings for selected wall or partition constructions.
Fire resistance is sometimes less when combustible members are framed into the wall because the internal
positioning reduces overall wall thickness. Heat is transmitted more rapidly through the smaller net wall
thickness and could ignite combustible construction on the other side. If the combustible members are
supported by pilasters and the wall thickness is not reduced, the full fire resistance of the wall is available.

Noncombustible members do not affect fire resistance when they are boxed in (not set in an open pocket).
However, stability may be a problem. (See Data Sheet 1-22.)
6.1 Masonry Walls
The fire endurance of masonry walls depends on the type of material and the thickness of the wall, if it is
solid. For hollow units, the term equivalent thickness is used. This is the thickness of a solid wall that could
be made from the same amount of material in the hollow wall if the material were recast into a solid mass.
The equivalent thickness may be computed using the following formula:
English units
Te = V/LH (Eq. 10)
SI units
Te = 1000V/LH (Eq. 10)
Where:
Te = equivalent thickness, in. (mm)
V = net volume (gross volume less volume of voids), in3
(cm3
)
L = length of masonry unit, in. (mm)
H = height of masonry unit, in. (mm)
Another method of calculating equivalent thickness if the percentage of solids is known, is to multiply the
percent solids times the actual thickness of the masonry unit. The actual thickness is generally 3⁄8-in. (10 mm)
less than the nominal thickness. For example, if it is known an 8 in. (203 mm) nominal thickness masonry
unit is 60% solid, the equivalent thickness would be:
Te = (8 - 3⁄8) x 0.60 = 7.625 x 0.60 = 4.6 in. English units
Te = (200 - 10) x 0.60 = 190 x 0.60 = 114 mm SI units
Mortar joints are not considered in the computations. See Table 6 for ratings for equivalent thickness based
on type of aggregate. Rated masonry units can be obtained with a laboratory certification of the equivalent
thickness and the materials. Other masonry units may be rated by fire tests.
For a conservative field estimate of the fire endurance of an existing wall, twice the face shell thickness can
be used as the equivalent thickness, Te. If the aggregate is unknown, assume it is siliceous gravel.

Table 6. Masonry Walls
Material
Thickness, in. (mm) and
Construction Details
Fire Endurance with No Combustible
Members Framed into Wall, hr1
NOMINAL
Brick (solid) 12 (300) all materials 10
8 (200) sand and lime 7
8 (200) clay and shale 5
8 (200) concrete 6
4 (100) clay and shale 11⁄2
4 (100) concrete and sand & lime 11⁄2
Hollow Tile: Partition tile2
12 (300) (two 6 in. [150 mm] tiles) 4
12 (300) (unknown number of cells) 3
8 (200) 2
Concrete Masonry Unit:
Unknown aggregate
16 (400) 4
12 (300) 3
8 (200) 13⁄4
EQUIVALENT THICKNESS
Concrete Masonry Unit:
Expanded slag or pumice aggregate
4.7 (119) 4
4.0 (102) 3
3.2 (81) 2
2.1 (53) 1
Expanded clay, shale or slate
aggregate
5.1 (130) 4
4.4 (112) 3
3.6 (91) 2
2.6 (66) 1
Limestone, cinders, or air-cooled slag
aggregate
5.9 (150) 4
5.0 (127) 3
4.0 (102) 2
2.7 (69) 1
Calcareous gravel aggregate 6.2 (157) 4
5.3 (135) 3
4.2 (107) 2
2.8 (71) 1
Siliceous gravel aggregate 6.6 (168) 4
5.5 (140) 3
4.4 (112) 2
2.9 (74) 1
Notes:
1. Where combustible members frame into the wall, the fire endurance rating is governed by the thickness of solid material between the
end of each member and the opposite face of the wall or between members set in from opposite sides.
2. Load-bearing hollow tile may be identified by its thicker walls. This tile will have a higher fire endurance rating than partition tile.
The following definitions apply to Table 6.
Siliceous gravels are grains or pebbles of quartz, chert, or flint.
Calcareous gravels are grains or pebbles of limestone and dolomite.
Cinders are residue of combustion.
Slag is the fused and vitrified matter separated during the reduction of a metal from its ore.
Expanded slag is cooled by pouring molten slag into water (as opposed to air cooled slag).
Expanded clay, shale or slate is produced by expanding the mined material in kilns. Vermiculites are in
this category.
Pumice is the porous or spongy form of volcanic glass.
Refer to Table 6.1 to determine the equivalent thickness of typical 2-core (2-cell) concrete masonry units
(CMU), which is the type used most often. If the type of CMU is unknown, and the % solid is unknown, assume
that CMU is 2-core and use Table 6.1 to determine equivalent thickness.

Refer to Table 6.2 to determine the equivalent thickness of typical 3-core (3-cell) CMU. Only use Table 6.2
when the CMU is verified and documented to be 3-core CMU.
Table 6.1 Equivalent Thickness and Minimum Face Shell Thickness of 2-Core Concrete Masonry Units*
Nominal Unit Thickness Actual Unit Thickness
Minimum Face Shell
Thickness Equivalent Thickness*
% Solid
(in.) (mm) (in.) (mm) (in.) (mm) (in.) (mm)
6 152 5.625 143 1.0 25 3.1 79 55
8 203 7.625 194 1.25 32 4.0 102 53
10 254 9.625 244 1.375 35 4.5 113 46
12 305 11.625 295 1.5 38 5.1 129 44
14 356 13.625 346 - - 5.5 139 40
16 406 15.625 397 - - 6.0 152 38
*Note: Equivalent thickness is approximate based on typical two-core concrete masonry units.
Table 6.2 Equivalent Thickness and Minimum Face Shell Thickness of 3-Core Concrete Masonry Units*
Nominal Unit Thickness Actual Unit Thickness
Minimum Face Shell
Thickness Equivalent Thickness*
% Solid
(in.) (mm) (in.) (mm) (in.) (mm) (in.) (mm)
4 102 3.625 92 0.75 19 2.7 69 74
6 152 5.625 143 1.0 25 3.3 84 59
8 203 7.625 194 1.25 32 4.3 109 56
10 254 9.625 244 1.375 35 5.3 135 55
12 305 11.625 295 1.5 38 6.3 160 54
*Note: Equivalent thickness is approximate based on three-core concrete masonry units.

6.1.1 Masonry Walls with Gypsum Wallboard or Plaster Finishes
Refer to Tables 6.3 and 6.4 to determine the additional fire endurance provided by finish materials on masonry
walls, with the following limitations:
• Where finishes are applied to the fire-exposed side or both sides of a masonry wall, the contribution to
the fire endurance of the finish materials is limited to not more than the fire endurance of the masonry
wall alone.
• The contribution to the fire endurance of the finish material on the non-fire exposed side of the wall is limited
to one-half the fire endurance of the masonry wall alone.
• If either side of the masonry wall can be fire-exposed, and the finish is not the same on each side of the
wall, then the fire endurance of the wall assembly must be calculated twice - with fire exposure at either
side - and the credited fire endurance will be the lesser calculated fire endurance.
Table 6.3 Fire Endurance Assigned to Finish Materials on the Fire- Exposed Side of Masonry Wall
Thickness (in. ) Time (min.)1
Gypsum Board
1/2 (13) 15
5/8 (16) 20
Type X Gypsum Board
1/2 (13) 25
5/8 (16) 40
Portland Cement-Sand Plaster on Metal Lath
1/2 (13) 10
3/4 (19) 20
1 (25) 30
Gypsum Sand Plaster on Metal Lath
1/2 (13) 20
3/4 (19) 50
1 (25) 75
Portland Cement-Sand Plaster, Gypsum Sand Plaster, or Vermiculite or Perlite Aggregate Plaster Applied Directly to
Masonry
≤ 5/8 (16) Add plaster thickness to the equivalent thickness of
masonry.
> 5/8 (16) Add plaster thickness of 5/8 in. (16 mm) to the equivalent
thickness of masonry.
Notes:
1. Add the fire endurance of the finish material to the fire endurance of the masonry wall to obtain the fire endurance for the wall assembly.
2. For gypsum board or plaster used with steel furring channels: Space the furring channels not more than 24 in. (610 mm) apart and
affix with masonry or concrete screws spaced not more than 12 in. (305 mm) apart. Space metal lath nails or screws not more than
12 in. (305 mm) apart along each furring channel.
3. For gypsum board attached directly to the masonry wall, use masonry or concrete screws spaced with 1 screw for each 2 ft2
(0.18 m2
)
of gypsum board.
4. Assume gypsum board is not Type X unless it can be verified.

Table 6.4 Factors for Finish Thickness on Non-Fire-Exposed Side of Masonry Wall
Finish Material
Type of Masonry
Solid Clay
Brick
Concrete Masonry of
Aggregate not
otherwise included in
this table or of
unknown aggregate
Concrete Masonry of
Expanded Shale,
Expanded Slate, or
Expanded Clay
Concrete Masonry of
Expanded Slag or
Pumice
Gypsum Board 3.0 2.5 2.25 2.0
Portland Cement-
Sand Plaster, Lime
Sand Plaster
1.0 0.75 0.75 0.5
Gypsum Sand
Plaster
1.25 1.25 1.0 1.0
Vermiculite or Perlite
Plaster
1.75 1.5 1.25 1.25
Notes:
1. Apply the factors in this table to the actual thickness of finish material on the non-fire- exposed side of the masonry wall to obtain the
equivalent thickness of the type of masonry shown.
2. Add the equivalent thickness of masonry from the finish material to the equivalent thickness of masonry wall to obtain total equivalent
thickness for determining the fire endurance of the wall assembly.
3. Do not credit any increase in fire resistance for finish materials affixed to hollow clay tile.
Example #1: Concrete masonry block (siliceous aggregate) wall with an equivalent thickness of 4.4 in. (112
mm). The fire endurance rating [R] without finishes is 2 hours (from Table 6).
a) Fire endurance rating with 1/2 in.(13 mm) Type X gypsum board affixed to the fire-exposed side only:
R = 2 hours + 25 minutes (from Table 6.3) = 2 hours, 25 min.
The fire endurance contribution of the Type X gypsum board (25 min.) does not exceed the fire endurance
of the masonry wall alone (2 hours); therefore, the fire endurance rating is acceptable.
b) Fire endurance rating with 1/2 in.(13 mm) gypsum board affixed to the non-fire-exposed side only:
Gypsum board Te = 1/2 in.(13 mm) x 2.5 (from Table 6.4) = 1.25 in. (32 mm)
Total Te = 4.4 in. (112 mm) + 1.25 (32 mm) = 5.65 in. (144 mm)
From Table 6, the approximate fire endurance is 3 hours for siliceous aggregate CMU with an equivalent
thickness of 5.5 in. (140 mm); therefore, say R = 3 hours.
The fire endurance contribution of the 1/2 in.(13 mm) gypsum board (1 hour) does not exceed one-half
the fire endurance of the masonry wall alone (1/2 x 2 hr); therefore, the fire endurance rating is acceptable.
c) Fire endurance rating with 1/2 in. (13 mm) Type X gypsum board affixed to both sides of the wall:
The Type X gypsum board on the fire-exposed side adds 25 minutes to the fire endurance, while the
gypsum board on the non-fire-exposed side adds approximately 1 hour; therefore, the fire endurance for
the entire wall assembly is:
R = 2 hrs + 25 min. + 1 hr = 3 hrs, 25 minutes
The fire endurance contribution of the gypsum board affixed to both sides of the wall (25 min + 1 hr) does
not exceed the fire endurance of the masonry wall alone (2 hr); therefore, the fire endurance rating is
acceptable.
6.1.2 Multiple-Wythe Masonry Walls
6.1.2.1 For masonry walls where two wythes (two layers or two leafs), of masonry make up the wall assembly,
and with no insulation between the wythes, the fire endurance of the wall assembly can be estimated based
in the fire endurance of the two individual components as indicated in Table 6.5.
For example, if the fire endurance of one wythe is 1 hour, and fire endurance for the adjacent wythe is 1.5
hours, then the fire endurance for the double-wythe wall assembly is 4 hours.

Table 6.5 Fire Endurance of Double-Wythe Masonry Wall
Fire Endurance of Double Wythe Wall (Hours)
Fire Endurance
of Wythe 2
(Hours)
Fire Endurance of Wythe 1 (Hours)
0.5 1 1.5 2 2.5 3
0.5 1.6 2.4 3.1 3.7 4.4 5.0
1 - 3.2 4.0 4.8 5.5 -
1.5 - - 4.9 5.7 - -
Linear interpolation is acceptable for reasonable approximations.
6.1.2.2 For multiple-wythe masonry walls with insulating material between the wythes (such as foamed plastic
or cellular plastic insulation, or mineral or glass fiberboard) in a masonry cavity wall, it is the responsibility
of the design professional or contractor to provide fire test results from a nationally recognized testing
laboratory to document adequate fire endurance.
Do not use wall assemblies that contain foamed plastic insulation for MFL fire walls. Refer to Data Sheet
1-22, Maximum Foreseeable Loss, for additional information.
6.1.3 Crediting Core Fill for CMU
6.1.3.1 Do not credit flowable loose material, such as pea stone or vermiculite, to fill the hollow cores of
CMU walls for the purposes of increasing fire endurance because these materials can flow from the cores
where masonry face shells become cracked or damaged.
6.1.3.2 Grout-Filled CMU
Only credit the enhanced fire resistance of grout-filled CMU walls when all the cores are filled solid with
cement grout.
For CMU made from siliceous or calcerous aggregates, and if all the cores are filled solid with cement grout,
assume that the CMU is 100% solid and the equivalent thickness (Te) is equal to the actual thickness of
the siliceous or calcerous aggregate CMU for determining fire resistance.
For CMU made from aggregates other than siliceous or calcerous, and if all the cores are filled solid with
cement grout, base the fire resistance of the wall on the method used in Section 6.1.1 and Table 6.4 by
assuming that the equivalent thickness of the cement grout portion (based on % solid) is evaluated as Portland
Cement-Sand Plaster on the non-fire-exposed side of the masonry wall.
6.1.4 Masonry Cover for Reinforcing
Cover for steel reinforcing (e.g., rebar) in masonry wall is provided by both the CMU face shell thickness
and the cement grout in the reinforced cores. Refer to Section 6.2.3 and use the same recommended cover
for load-bearing CMU walls as for concrete walls with siliceous aggregate.
6.2 Concrete Walls
The recommendations in this section apply to cast-in-place, site cast (e.g., tilt-up), and precast concrete.
6.2.1 Fire Endurance of Concrete Walls
Refer to Table 7 to estimate the fire endurance of concrete walls.

Table 7. Fire Endurance and Minimum Thickness of Concrete Walls
Concrete Aggregate
Type
Fire Endurance (Hours)
1 1.5 2 3 4
Minimum Thickness
in. mm in. mm in. mm in. mm in. mm
Siliceous 3.5 89 4.3 109 5.0 127 6.2 157 7.0 178
Calcerous 3.2 81 4.0 102 4.6 117 5.7 145 6.6 168
Lightweight 2.7 69 3.3 84 3.8 97 4.6 117 5.4 137
Note: Where combustible members frame into the wall, the fire endurance rating is governed by the thickness of solid
concrete material between the end of each member and the opposite face of the wall or between members set in
from opposite sides.
6.2.2 Concrete Walls with Gypsum Wallboard or Plaster Finishes
Refer to Section 6.1.1, and use the same limitations (the fire endurance contribution of finish materials applied
to masonry wall) for concrete walls.
Refer to Table 6.3 and use the same recommended additive fire endurance for concrete walls for finish
materials applied to the fire-exposed side of the concrete wall. For finish materials applied to the non-fire-
exposed side of a concrete wall, refer to Table 7.1.
Table 7.1 Factors for Finish Thickness on Non-Fire-Exposed Side of Concrete Wall
Finish Material
Type of Aggregate used in Concrete
Siliceous or Calcerous Lightweight
Gypsum Board 3.0 2.5
Portland Cement-Sand Plaster, Lime
Sand Plaster
1.0 0.75
Gypsum Sand Plaster 1.25 1.0
Vermiculite or Perlite Plaster 1.75 1.25
Notes:
1. Apply the factors in this table to the actual thickness of finish material on the non-fire- exposed side of the concrete wall to obtain the
equivalent thickness of the type of concrete shown.
2. Add the equivalent thickness of concrete from the finish material to the equivalent thickness of concrete wall to obtain total equivalent
thickness for determining the fire endurance of the wall assembly.
6.2.3 Concrete Cover
Provide concrete cover of steel reinforcement for walls as indicated in Table 7.2. If calcerous aggregate or
lightweight aggregate concrete cannot be verified, assume the concrete is normal weight with siliceous
aggregate.
Adequate thickness of concrete cover is dependent on two characteristics: the type of concrete (based on
concrete density or type of aggregate), and the type of reinforcement the concrete cover is protecting.

Table 7.2 Minimum Concrete Cover of Steel Reinforcement for Fire Resistance of Concrete Walls
Type of
Reinforcement
Fire
Resistance
(Hours)
Minimum Concrete Cover
Normal Weight Aggregate Lightweight Aggregate
Siliceous Calcerous
(inch) (mm) (inch) (mm) (inch) (mm)
Rebar 1 3/4 19 1/2 13 1/2 13
1.5 1 25 3/4 19 3/4 19
2 1 25 3/4 19 3/4 19
3 1 1/4 32 1 1/4 32 1 1/4 32
4 1 3/4 44 1 1/2 38 1 1/4 32
P/S Strand
or P/T
Tendon
1 1 1/4 32 1 25 1 25
1.5 1 1/2 38 1 1/2 38 1 1/4 32
2 2 51 1 3/4 44 1 1/2 38
3 2 1/2 64 2 1/4 57 2 51
4 3 76 2 3/4 70 2 1/2 64
Notes:
(1) Concrete cover is to the main longitudinal reinforcement; not to ties or stirrups.
(2) Note that concrete cover prescribed by structural concrete codes/standards for normal (non-fire) durability may exceed the values in
this table; the greater cover values shall govern.
(3) Rebar is hot-rolled steel reinforcing bar.
(4) P/S Strand is high-strength cold-drawn steel prestressing strand.
(5) P/T Tendon is high-strength cold-drawn steel post-tensioning tendon.
Note that concrete cover is the thickness of concrete measured from the face of the wall to the outer surface
of the main longitudinal reinforcing closest to the face of the wall.
6.2.4 Multiple-Wythe Concrete Walls
6.2.4.1 For concrete walls of multiple-wythe or multiple layers such as concrete sandwich panels, follow the
recommendations in Section 6.1.2.
For concrete walls where two wythes, or two layers, of concrete make up the wall assembly, the fire endurance
of the wall assembly can be determined, similar to that of masonry walls, based in the fire endurance of
the two individual components as indicated in Table 6.5.
6.2.4.2 For multiple-wythe concrete walls with combustible insulating material between the wythes (such as
foamed or cellular plastic insulation), it is the responsibility of the design professional or contractor to provide
fire test results from a reputable testing laboratory to document adequate fire endurance.
Do not use wall assemblies that contain foamed plastic insulation for MFL fire walls. Refer to Data Sheet
1-22, Maximum Foreseeable Loss, for additional information.
6.2.5 Precast Concrete Walls
Precast concrete walls are made up of individual precast concrete units. The fire endurance rating of
precast/prestressed concrete wall panels can be determined both by testing and analytical methods.
Acceptable analytical methods are outlined in ″Design for Fire Resistance of Precast Prestressed Concrete″
published by the Prestressed Concrete Institute; however, do not credit foamed plastic, or cellular plastic,
insulation (such as in a concrete sandwich panel) as enhancing or increasing the fire resistance rating of the
wall.
Follow the recommendations in Section 6.2.4 for multi-wythe concrete walls.

6.3 Solid Partitions
The fire endurance rating of various solid, nonbearing partitions can be found in Table 8.
Table 8. Solid Nonbearing Patitions
Construction Material and Thickness
Fire
Endurance,
hour
Added
Resistance,
Both Sides
Plastered1
,
hour
Solid Partition, steel frame. Metal lath on 3⁄4 in.
(19 mm) steel channels
11⁄2 in. (38 mm) perlite gypsum 1
–
2 in. (51 mm) fibered gypsum plaster 13⁄4
2 in. (51 mm) sanded gypsum 1:11⁄2 11⁄2
21⁄4 in. (57 mm) fibered gypsum
plaster
2
2 in. (51 mm) Cement plaster 1⁄2
21⁄2 in. (64 mm) sanded gypsum
1:11⁄2 perlite or vermiculite
2
21⁄2 in. (64 mm) fibered gypsum 21⁄2
Solid Partition. Lath only. (Temporary bracing
channels used in erection)
2 in. (51 mm) vermiculite or perlite
plaster on 1⁄2 in. (13 mm) gypsum or
metal lath
2
–
11⁄2 in. (38 mm) sanded gypsum on
1⁄2 in. (13 mm) gypsum or metal lath
1
11⁄2 in. (38 mm) perlite or vermiculite
on 1⁄2 in. (13 mm) gypsum or metal
lath
11⁄2
Solid Partition 4 layers 1⁄2 in. (13 mm) type X
gypsum board2
2
–
5 layers 1⁄2 in. (13 mm) type X
gypsum board2
3
gypsum board
21⁄2 –
Notes:
1. When plastered on both sides with 1⁄2 in. (13 mm) 1:3 gypsum-sand plaster.
2. Type X gypsum board denotes boards made with a specially formulated gypsum core that provides greater fire endurance than regular
gypsum of equal thickness.
Plaster thickness, referred to in the tables, is measured from the face of the metal lath to the exposed face of the plaster. Plaster
proportions are given in the tables as weights of dry plaster to dry sand, the first ratio being for the scratch or base coat and the second
for the brown or finish coat. Mixtures richer in plaster may be substituted for those given. Plaster noted as ‘‘neat’’ is to be taken as gypsum
plaster containing no aggregate.
Plasters often contain vermiculite or perlite lightweight aggregate. Mixtures containing either of these aggregates have a greater fire
resistance than those containing sand. In the tables, the ratios following the plaster mix opposite these types of plaster indicate the number
of cubic feet (0.028 m3
) of vermiculite or perlite per 100 pounds (45 kg) of fibered gypsum.

Table 8. Solid Nonbearing Partitions (cont’d.)
Construction Material and Thickness
Fire
Endurance,
hour
Added
Resistance,
Both Sides
Plastered1
,
hour
gypsum board on each side of steel
column (column supports panel only) 3 –
2 layers 1⁄2 in. (13 mm) type X
gypsum board on each side of steel
column (column part of building
frame) 2 –
Solid Partition 2 layers each 3⁄4 in. (19 mm) thick
(actual) T&G boards, one side of
wood studs, joints staggered
1⁄4
–
21⁄2 in. (64 mm) gunite on reinforced
mesh
1⁄2
2 in. (51 mm) solid gypsum blocks 1
3 in. (76 mm) solid gypsum blocks 3
3 in. (76 mm) gypsum blocks 70%
solid
1 1
4 in. (102 mm) gypsum partition
blocks 70% solid
1 2
5 in. (127 mm) solid gypsum partition
blocks
4 2
4 in. (102 mm) clay partition tile
(1-cell)
1⁄4 1⁄2
4 in. (102 mm) cinder aggregate CMU
65% solid
1 1
6 in. (152 mm) cinder aggregate CMU
60% solid
11⁄4 3⁄4
Notes:
1. When plastered on both sides with 1⁄2 in. (13 mm) 1:3 gypsum-sand plaster.
2. Type X gypsum board denotes boards made with a specially formulated gypsum core that provides greater fire endurance than regular
gypsum of equal thickness.
Plaster thickness, referred to in the tables, is measured from the face of the metal lath to the exposed face of the plaster. Plaster
proportions are given in the tables as weights of dry plaster to dry sand, the first ratio being for the scratch or base coat and the second
for the brown or finish coat. Mixtures richer in plaster may be substituted for those given. Plaster noted as ‘‘neat’’ is to be taken as gypsum
plaster containing no aggregate.
Plasters often contain vermiculite or perlite lightweight aggregate. Mixtures containing either of these aggregates have a greater fire
resistance than those containing sand. In the tables, the ratios following the plaster mix opposite these types of plaster indicate the number
of cubic feet (0.028 m3
) of vermiculite or perlite per 100 pounds (45 kg) of fibered gypsum.

6.4 Hollow Partitions
6.4.1 It is the responsibility of the design professional or contractor to provide fire test results from a nationally
recognized testing laboratory to document adequate fire endurance. Alternatively, refer to Table 9 and Table
10 for various hollow partition walls, or to the ASTM E 119 Specification Tested section in the Approval Guide
for acceptable wall assemblies.
6.4.2 Where insulation is needed in hollow partition walls, use non-combustible insulation such as glass fiber
or mineral fiber.
Table 9. Hollow Nonbearing Partitions
Construction Material and Thickness (each side)
Fire Resistance,
hr
Plaster and metal lath on metal studs 1 in. (25 mm) neat gypsum 21⁄2
1 in. (25 mm) perlite gypsum 2
1 in. (25 mm) sanded gypsum 1:1⁄2 2
7⁄8 in. (22 mm) sanded gypsum 1:11⁄2 11⁄2
7⁄8 in. (22 mm) portland cement 1:2-1:3 1
3⁄4 in. (19 mm) neat gypsum 11⁄2
3⁄4 in. (19 mm) sanded gypsum 1:2 1
3⁄4 in. (19 mm) portland cement 1:2-1:3 1⁄2
Plaster and metal lath on cellular steel core 3⁄4 in. (19 mm) gypsum and sand plaster
on metal lath on cellular steel core. (Core
is not filled.) Use same rating for
load-bearing partitions.
1
Plaster and metal lath on metal studs 1 in. (25 mm) perlite gypsum 2
13⁄4 in. (44 mm) vermiculite (1⁄4:3⁄4:3⁄4) 5

Table 10. Stud Walls and Partitions, Bearing and Nonbearing 3
Construction
Material and Thickness
(Each side or one side)
Fire
Resistance,
hr
Added
Resistance,
Partition
Filled With
Mineral
Wool, hr
Plasterless type on one side only 1⁄2 in. (13 mm) type X gypsum board 1⁄4
5⁄8 in. (16 mm) type X gypsum board 1⁄3
Plasterless type on both sides 1⁄2 in. (13 mm) (actual) T&G sheathing boards 1⁄4 1⁄4
3⁄4 in. (19 mm) (actual) T&G sheathing boards 3⁄8 3⁄8
1⁄4 in. (6 mm) fir plywood 1⁄4 1⁄2
1⁄2 in. (13 mm) fiberboard (fire retardant treated) 1⁄2
3⁄8 in. (10 mm) type X gypsum board 1⁄2
3⁄8 in. (10 mm) type X gypsum board (2 layers)1
1
1⁄2 in. (13 mm) type X gypsum board1 3⁄4 1⁄4
11⁄2
5⁄8 in. (16 mm) type X gypsum board2
1
2
3⁄16 in. (5 mm) cement-asbestos board 1⁄6 1⁄2
3⁄16 in. (5 mm) cement-asbestos board over
3⁄8 in. (10 mm) gypsum board
1
3⁄16 in. (5 mm) cement-asbestos board over
1⁄2 in. (13 mm) gypsum board1
11⁄2
Plaster and lath on both sides 1⁄2 in. (13 mm) lime plaster, wood lath 1⁄2 1⁄4
1⁄2 in. (13 mm) sanded gypsum, wood lath 1⁄2 1⁄2
3⁄4 in. (19 mm) cement plaster on metal lath 1⁄2
3⁄4 in. (19 mm) sanded gypsum on metal lath 1 1⁄2
3⁄4 in. (19 mm) neat gypsum plaster on metal
lath
11⁄2
1 in. (25 mm) portland cement plaster asbestos
3 lb (1.36 kg) per sack (42.6 kg) on metal lath
1
1 in. (25 mm) neat gypsum on metal lath 2
1⁄2 in. (13 mm) sanded gypsum on 3⁄8 in.
(10 mm) plain or perforated gypsum lath
1
1⁄2 in. (13 mm) perlite or vermiculite plaster on
3⁄8 in. (10 mm) perforated gypsum lath
11⁄2
1 in. (25 mm) perlite plaster on 3⁄8 in. (10 mm)
perforated gypsum lath
2
Plaster and lath on one side only 3⁄4 in. (19 mm) vermiculite plaster on metal lath 3⁄8
9⁄16 in. (14 mm) perlite plaster on 3⁄8 in. (10 mm)
perforated gypsum lath
1⁄2
Notes:
1. For nonbearing partitions
2. Same with steel studs
T & G = Tongue and groove
3. For gypsum board applications, stagger the gypsum board joints of adjacent layers at least 12 in. (305 mm).

6.4.3 Type X Gypsum Board
Pure gypsum contains approximately 20% water within the calcium silicate crystal structure. When exposed
to fire, it releases the water gradually which helps a board to resist fire. In Standard Time-Temperature fire
tests this typically takes 10 minutes to vaporize the water from a 1⁄2 in. (13 mm) thick board. As the water vapor
is released, gypsum board looses some of its strength. To maintain the board’s integrity and to extend its
fire resistance, glass fiber reinforcement is included in the manufacture of certain boards. In the USA these
are referred to as type X gypsum wall boards.
ASTM C 36 defines type X gypsum board as any gypsum board that provides not less than 1 hr fire resistance
for boards 5⁄8 in. (16 mm) thick, or not less than 3/4 hr fire resistance for boards 1⁄2 in. (13 mm) thick when
applied on each side of wood studs 16 in. (406 mm) on center and tested in accordance with ASTM E 119.
Outside the USA manufacturers and standards organizations may not use the term type X. It is important to
ensure when a locally manufactured gypsum board is being used, it is equivalent to the type X specified
in FM Global data sheets. As various thicknesses are made, it is also important to provide at least the
minimum thickness recommended in the loss prevention data sheet.
6.5 Wall Joints
Joints between wall panels must be protected. Some building codes may allow a lesser degree of protection
than is afforded by the wall panel. For instance, a 4-hr fire rated panel wall may have openings protected
with 3-hr rated fire doors. Based on the same logic, these codes allow the joints between panels to have a
rating of only 3/4 that of the wall panels. The basis for this allowance is that there will generally be open
space for personnel or vehicle traffic on either side of an opening and so it is less likely there will be
combustibles to ignite. This does not apply for panel joints. Combustible storage may be placed directly
against the wall at a joint. Therefore, FM Approvals recommends the joint treatment have the same fire
endurance rating as the wall panels.
Fire tests of wall panel joints showed that fire endurance, as determined by temperature rise of 325°F (181°C)
over the joint, is influenced by joint type, joint treatment, joint width, and panel thickness. A typical joint
treatment is shown in Figure 3. Typically, a ceramic fiber blanket is used to provide the necessary fire
endurance.
6.6 Autoclaved Aerated Concrete (AAC) Walls
AAC is provided in both block and panel units. AAC blocks generally have a maximum height of 8-in. (200
mm) and a maximum length of 24-in. (600 mm). AAC panel can be considered any AAC unit that exceeds the
size restrictions of AAC block.
The dry weight density of AAC ranges from approximately 25 pcf (4.2 kN/m3
) to 50 pcf (8.4 kN/m3
) with
corresponding compressive strengths of approximately 350 psi to 900 psi (2.4 MPa to 6.2 MPa).
Fig. 3. Section view of proprietary fire-rated joint detail.

6.6.1 Reference Material and Design Specifications and Standards
Use AAC block and AAC panels that comply with the requirements of nationally recognized material
standards, such as ASTM C1452 (block) and ASTM C1386 (panel).
6.6.2 Fire Tests of AAC Walls
Use only AAC block and AAC panel fire wall assemblies that have been documented as passing a nationally
accepted fire test, such as ASTM E 119 or UL 263, for the required fire endurance.
6.6.3 Minimum Requirements for AAC Walls
In addition to the recommendations in Sections 6.6.1 and 6.6.2, follow the recommendations in this Section
as noted below:
6.6.3.1 For load-bearing walls, use AAC blocks and AAC panels that are:
a) not less than 5.9 in. (150 mm) thick where required fire endurance is 2 hours to 4 hours; or
b) not less than 3.9 in. (100 mm) thick where required fire endurance is less than 2 hours.
6.6.3.2 For non-load-bearing walls, use AAC blocks and AAC panels that are:
a) not less than 3.9 in. thick (100 mm) where required fire endurance is 2 hours to 4 hours; or
b) not less than 2.9 in. thick (75 mm) where required fire endurance is less than 2 hours.
6.6.3.3 For steel (non-prestressed) reinforcement in AAC blocks or panels, provide:
a) not less than 1.0-in. (25 mm) of AAC clear cover where fire endurance of 2 hours to 4 hours; or
b) not less than 3⁄4-in. (19 mm) of clear cover where required fire endurance is less than 2 hours.
6.6.3.4 Provide AAC plain blocks and AAC panels that are solid AAC; or, for AAC reinforced blocks that are
not solid AAC (e.g., U-block with horizontal reinforcement, or O-block with vertical reinforcement), ensure
that not less than one-half the total wall thickness is AAC, with the balance of the wall thickness filled solid
with cement-based grout.
6.6.3.5 Provide AAC block and AAC panel wall assemblies with thin-bed cement-based mortar on all joint
surfaces.
6.6.3.6 Provide AAC block walls with staggered vertical joints (e.g., running bond or offset bond).
6.6.3.7 Provide AAC panel walls with staggered vertical joints except where the AAC panels are supported
by, or mechanically attached to, structural members (such as reinforced concrete columns or beams) with
adequate fire resistance ratings.
6.7 Fire-Rated Glazing
Glazing is often used in fire doors (door lites or vision panels) and fire walls (windows). Codes generally
limit the size of individual glazing areas for fire doors and limit the aggregate glazing area for fire walls. The
acceptance criteria of standard fire tests - such as UL 9 (NFPA 257) for window assemblies, or UL 10B and
UL 10C (NFPA 252) for fire door assemblies - do not have limitations on the temperatures of the unexposed
surfaces; that is, the acceptance criteria are based on a fire integrity rating alone, but not a fire insulating
rating.
UL differentiates between the two general groupings of fire-rated glazing assemblies as:
• ″Fire-Protection-Rated Glazing Materials″ listed assemblies that are based on a fire integrity rating, but
not an insulating rating (i.e., there is no limitation on temperatures on the unexposed surfaces, and a hose
stream test is not required); and
• ″Fire-Resistance-Rated Glazing Materials″ listed assemblies that must meet UL 263 (ASTM E 119) and
therefore must have not only adequate fire integrity but also an adequate fire-insulating rating, as well
as adequate resistance to hose stream exposure where applicable (i.e., the same performance criteria as
for fire-rated wall assemblies).

The International Building Code (IBC) has developed a marking system for fire-rated glazing, and those
glazing assemblies that meet fire-resistance ratings for walls (tested to ASTM E 119 or UL 263), that include
an adequate insulating rating, as well as adequate resistance to hose stream exposure where applicable,
will carry a permanent ″W″ mark along with the fire endurance in minutes on the glazing. For example: a
2-hour fire-resistance-rated glazing assembly will carry a ″W-120″ permanent mark on the glazing.
There are three types of fire-rated glazing pertinent to the scope of this data sheet. They are:
a) Wired Glass
Minimum 1⁄4-in. (6 mm) polished wired glass is routinely specified in fire doors and fire-rated partitions. Wired
glass is made up of annealed glass and a mild steel wire mesh. The mesh pattern may be square, rectangular,
diamond shaped or hexagonal. The wire mesh is normally centered in the glass. Wired glass has a fire
protection rating for integrity (ability to remain in the frame to prevent tha passage of flame or hot gasses)
of approximately 45 minutes. It has no appreciable insulating value and therefore no fire insulating rating.
In tests using the standard time-temperature curve of ASTM E 119, wired glass cracks within minutes of the
start of the test. The wire mesh holds the fractured glass in place, preventing the passage of flame or gas.
At approximately 45 minutes, the furnace temperatures exceed 1600°F (870°C) and the glass starts to
become viscous and slumps out of the frame.
b) Fire-Resistant Glazing
This category includes monolithic borosilicate or calcium-silica tempered glass, ceramic glazing, and
laminated glazing. These products do not have any embedded wire mesh. They may be listed by some
third-party testing agency as having a fire protection rating ranging from 20 to 90 minutes. However, like wired
glass, they do not meet the temperature rise limitations of ASTM E 119 (NFPA 251, UL 263) and therefore
have no fire insulating rating. The fire protection rating refers only to the glazing’s integrity rating and ability
to meet criteria on the size of openings that develop.
c) Insulating Fire-Resistant Glazing
This category includes glazing materials that are intended to provide some insulating value. Proprietary
products are available that consist of two or more layers of tempered glass separated by steel spacers. The
cavity between the glass layers is typically filled with an aqueous gel or intumescent material.These gels
and intumescent materials are transparent at ambient temperatures but become opaque when exposed to
fire and thus become a barrier to radiation as well as being a thermal barrier. These products have been tested
and meet the acceptance criteria of ASTM E 119. Therefore, these assemblies can be used as equivalently
rated fire walls provided the construction details of the tested assemblies are followed in order to ensure
the proper fire resistance rating is achieved; these details will include a maximum glazing area and maximum
glazing width or height between the support framing for the tested assembly. This category of insulating
fire-resistant glazing would be classified by UL to be ″Fire-Resistance-Rated Glazing Materials″. Fire
endurance ratings of up to 3 hours are available.
When temperatures fall below 5°F (-15°C) or exceed 104°F (40°C), the insulating gel may become cloudy
or opaque. Therefore, for exterior wall uses, additional exterior glazing protection designed to maintain the
insulating fire-resistant glazing at acceptable temperatures may be necessary.
Refer to Data Sheet 1-20, Protection Against Exterior Fire Exposure, and Data Sheet 1-22, Maximum
Foreseeable Loss, for recommendations regarding exterior walls, MFL subdivisions, and glazing for fire doors,
respectively.
7.0 ROOF-CEILING ASSEMBLIES
Roof-ceiling assemblies are tested and rated as assemblies. All components of a given assembly must be
provided (unless described as optional) for the assembly to attain the rating. Where there are openings or
penetrations (HVAC grills, electrical fixtures, etc.), the listing will provide additional information or limitations
on their protection. The rating is, of course, for the entire assembly. The assembly is tested with the underside
of the ceiling exposed to the furnace and temperature rise readings are taken on the top surface of the roof.
Provide joint treatments with fire endurance ratings not less than the fire endurance rating needed for the
roof-ceiling assembly.

8.0 FLOOR-CEILING ASSEMBLIES
Floor-ceiling assemblies are tested and rated as assemblies. All components of a given assembly must be
provided (unless described as optional) for the assembly to attain the rating. The rating is for the entire
assembly. The assembly is tested with the underside of the ceiling exposed to the furnace and temperature
rise readings are taken on the top surface of the floor above.
Tables 11 through 16 give fire endurance ratings of commonly used floor constructions. The tabulated ratings
are only for the types of construction illustrated or described. Where there are air-conditioning ducts, electric
raceways, or other openings, the rating of the floor many depend upon the protection at the openings and
not upon the floor construction itself. The membrane used in new wood floor constructions between the
finished and rough flooring should preferably be an 11 lb/100 ft2
(0.6 kg/m2
) glass fiber felt.
The principal factors affecting the fire endurance of prestressed concrete are the amount of concrete cover
over the prestressing tendons and the cross sectional area of the member.
8.1 Provide joint treatments with fire endurance ratings not less than the fire endurance rating needed for
the floor-ceiling assembly.
8.2 Refer to Table 7 to determine the minimum thickness of flat concrete floor slabs of uniform thickness,
including cast-in-place, precast, precast/prestressed, and post- tensioned concrete, for the needed fire
endurance rating. For floor-ceiling assemblies that are not flat concrete slabs of uniform thickness, refer to
Tables 14, 15, or 16 for the fire resistance of various assemblies; or use an assembly that has been verified
and documented by fire tests results performed by a nationally recognized testing lab to provide the needed
fire endurance.
8.3 For precast/prestressed hollow-core plank, or other types of slabs with hollow cores or cells, use an
equivalent thickness (Te) based on the portion the cross-section that is solid concrete, similar to how Te is
calculated for CMU.
8.4 Use noncombustible insulating materials, such as lightweight insulating concrete, to fill the voids in
hollow-core concrete plank and other voided slabs when additional thermal resistance is needed. Avoid the
use of foamed plastic (cellular plastic) insulation in hollow core plank and other voided slabs unless adequate
fire endurance has been verified and documented by fire tests results performed by a nationally recognized
testing lab.
It is important that the fire-tested assembly accurately represent the as-built construction, particularly the
details at the end conditions or boundary conditions.
8.5 Refer to Tables 14 and 15 for concrete cover of steel reinforcement for cast-in-place and precast concrete
floors, respectively. For floor slabs not shown in Tables 14 and 15 (e.g., flat slabs of uniform thickness), refer
to Table 7.2 to determine the concrete cover for the needed fire endurance. Alternatively, use a concrete
cover based on a tested assembly as verified by fire test results.
Table 11. Fire Resistance of Plank-on-Timber Floors
Construction
Fire Resistance,
hr:minutes
Ordinary Plank Tongue & Groove mill flooring
25⁄8 in. (67 mm) actual 0:45
35⁄8 in. (92 mm) actual 1:00 (est.)
Laminated Plank
d = actual size
35⁄8 in. (92 mm) 0:45

Table 12. Fire Resistance of Wood-Joisted Floors
Construction
Plaster Mix
Type of Ceiling
Fire
Resistance,
hr:minutes
Base
Coat
Finish
Coat
Flooring to consist of two layers of
25⁄32 in. (10 mm) Tongue & Groove
Sheathing
None None 0:15
None 1⁄2 in. (13 mm) gypsum wallboard 0:25
None 2 layers 3⁄8 in. (10 mm) gypsum wallboard 0:30
None 1⁄2 in. (13 mm) type X gypsum wallboard 0:45
None 2 layers 1⁄2 in. (13 mm) gypsum wallboard 1:00
None Same, with 1 in. (25 mm) wire fabric
between
1:00
None 5⁄8 in. (16 mm) type X gypsum board 1:00
1:2 1:2 3⁄8 in. (10 mm) perforated gypsum lath
and 1⁄2 in. (13 mm) sanded gypsum
plaster
0:30
Same, with 1⁄2 in. neat gypsum plaster 0:45
1:4 1:2 Wood lath 5⁄8 in. (16 mm) lime plaster 0:30
1:2 1:3 Wood lath 1⁄2 in. (13 mm) sanded gypsum
plaster
0:35
1:2 1:3 Metal lath fastened with 11⁄4 in. (32 mm)
long, No. 11 gage (3.06 mm), 3⁄8 in.
(10 mm) head, barbed roofing nails and
3⁄4 in. (19 mm) sanded gypsum plaster
0:45
Same, except fastened with 11⁄2 in.
(38 mm) long, No. 11 gage (3.06 mm),
7⁄16 in. (11 mm) head, barbed roofing
nails
1:00
11⁄2-2:1 11⁄2-3:1 Metal lath fastened with 11⁄2 in. (38 mm)
long No. 11 gage (3.06 mm), 7⁄16 in.
(11 mm) head, barbed roofing nails and
3⁄4 in. (19 mm) vermiculite plaster
1:45
21⁄2:1 3:1 3⁄8 in. (10 mm) gypsum lath and 1 in.
(25 mm) wire mesh, 1⁄2 in. (13 mm)
gypsum perlite plaster
1:30

Table 13. Fire Resistance of Steel-Joisted Floors
Floor
Construction
Plaster Mix Ceiling Construction
(on metal lath except
where otherwise
noted)
Fire
Resistance,
hr:minutes
Base
Coat
Finish
Coat
1 layer sheathing 1:2 1:3 3⁄4 in. (19 mm)
sanded gypsum
plaster
0:45
2 layers sheathing 1:2 1:3 3⁄4 in. (19 mm)
sanded gypsum
plaster
1:00
2 in. (51 mm)
reinforced concrete
on metal lath
2:1 3:1 5⁄8 in. (16 mm)
gypsum perlite on
3⁄8 in. (10 mm)
perforated gypsum
lath secured to
furring channels
1:00
2 in. (51 mm)
reinforced concrete
1:2 1:3 3⁄4 in. (19 mm)
portland cement
plaster or 3⁄4 in. (19
mm) sanded gypsum
1:30
2 in. (51 mm) precast
reinforced gypsum
tile
1:2 1:3 3⁄4 in. (19 mm)
portland cement
plaster or 3⁄4 in. (19
mm) sanded gypsum
1:30
21⁄2 in. (64 mm)
reinforced concrete
1:2 1:3 3⁄4 in. (19 mm)
sanded gypsum
plaster
2:00
21⁄2 in. (64 mm)
reinforced concrete
1:2 1:2 1 in. (25 mm) sanded
gypsum plaster
2:30
2 in. (51 mm)
reinforced concrete
2:1 3:1 1 in. (25 mm) neat
gypsum plaster or 3⁄4
in. (19 mm) gypsum
vermiculite plaster
2:30
reinforced gypsum
tile with
1⁄4 in. (mm) cement
mortar finish
2:1 3:1 1 in. (25 mm) neat
in. (19 mm) gypsum
vermiculite plaster
2:30
21⁄2 in. (64 mm)
reinforced concrete
2:1 3:1 1 in. (25 mm) neat
in. (19 mm) gypsum
vermiculite plaster
3:00
reinforced gypsum
tile with
1⁄2 in. (12 mm)
cement mortar finish
2:1 3:1 1 in. (25 mm) neat
in. (19 mm) gypsum
vermiculite plaster
3:00
21⁄2 in. (64 mm)
reinforced concrete
2:1 3:1 1 in. (25 mm)
gypsum vermiculite
plaster
4:00
reinforced gypsum
tile with 1⁄2 in. (13
mm) cement mortar
finish
2:1 3:1 1 in. (25 mm)
gypsum vermiculite
plaster
4:00
2 in. (51 mm)
reinforced concrete
1:3 2 in. (51 mm) precast
reinforced gypsum
tile covered with 1⁄2
in. (13 mm) gypsum
plaster
4:00

Table 14. Fire Resistance of Reinforced Concrete Floors
Construction
Slab
Thickness,
in. (mm)
t,
Protection
of
Reinforcement2
,
in. (mm)
Ceiling
Fire
Resistance,
hr
Reinforced concrete on cast-in-place or
precast joists
3
(76)
3⁄4
(19)
slab
11⁄2
(38)
joists
None 1
2
(51)
3⁄4
(19)
slab and
joists
3⁄4 in.
(19 mm)
gypsum
vermiculite1
3
3
(76)
3⁄4
(19)
slab and
joists
1 in.
(25 mm)
gypsum
vermiculite1
4
Reinforced concrete with cementitious mixture
protection
21⁄2
(64 mm)
3⁄4
(19)
7⁄8 in.
(22 mm)
type MK
vermiculite
plaster
2
Notes:
1. Metal-lath-and-plaster ceiling. Slab thickened 2 in. (51 mm) where there is an underfloor duct system.
2. Measured from the surface of concrete to the bottom of reinforcement.

Table 15. Fire Resistance of Prestressed Concrete Units
Construction
Maximum
Unit
Width,
ft (m)
Minimum Concrete
Cover Over Wires,
in. (mm)
Minimum
Wire
Spacing
at Ends,
in. (mm)
Minimum Concrete
Topping Over Unit,
in. (mm)
Fire
Resistance
Rating, hr1
Normal
Weight
Light-
weight
10
(3.05)
15⁄8 (41) bottom
2 (51) side
2
(51)
3-31⁄4
(76-83)
2
10
(3.05)
15⁄8 (41) bottom
2 (51) side
2
(51)
21⁄2
(64)
3
8
(2.44)
15⁄8 (41) bottom
11⁄8 (29) side
2
(51)
3-31⁄4
(76-83)
2
(51)
2
4
(1.22)
11⁄2 (38) plus
1 (25)
sprayed
vermiculite
2
(51)
3
Normal
Weight
Light-
Weight
None None 1
1
(25)
1
(25)
2
(51)
None None 2
3
(76)
2
(51)
None None 21⁄2
3
(76)
None None 3
Note: 1. Where a lightweight aggregate concrete has been used, ratings may be increased 20%.

Table 16. Fire Resistance of Composite Floors
Construction Floor
Plaster Mix
Ceiling
Fire
Resistance,
hr
Base
Coat
Finish
Coat
Reinforced concrete with tile fillers 4 or 6 in. (102 or
152 mm) tile and
11⁄2 in. or 2 in. (38
or 51 mm)
concrete
– – None 1
4 in. (102 mm) tile
and 11⁄2 in. (38
mm) concrete
– 1:3
5⁄8 in. (16 mm)
sanded gypsum
plaster
11⁄2
6 in. (152 mm) tile
and 2 in.
(51 mm) concrete
– 1:3
5⁄8 in. (16 mm)
sanded gypsum
plaster
2
Concrete on cellular steel floor on steel
beams. Cellular section 31⁄8 in. (79 mm)
thick
2 in. (51 mm)
concrete, d=9 in.
(229 mm)
2:1 3:1
1 in. (25 mm) neat
gypsum on metal
lath
4
When d is less
than 9 in. and
more than 2 in. (51
mm), reduce time
1 hr.
2:1 3:1
1 in. (25 mm)
gypsum perlite or
vermiculite on metal
lath
5
thick
2 in. (51 mm)
perlite or
vermiculite
concrete, d=3 in.
(76 mm)
2:1 31⁄2:1
1 in. (25 mm)
gypsum perlite or
plaster and beam
encased with same
4
2 in. (51 mm)
gravel concrete,
d=41⁄2 in. (114 mm)
– –
1 in. (25 mm)
sprayed asbestos
fiber1
3
Same – –
Beam rating: beam
protected with 1 in.
(25 mm) asbestos
fiber1
2
21⁄2 in. (64 mm)
gravel concrete,
d=71⁄4 in. (184
mm)
2-21⁄2:1 3-3¼:1
11⁄8 in. (29 mm) total
thickness: 5⁄8 in. (16
mm) gypsum
vermiculite plaster
and 1⁄2 in. (13 mm)
vermiculite acoustic
plaster, with beam
encased with same
4
beams. Cellular section 6 in. (152 mm)
thick
2 in. (51 mm)
cinder concrete
2-21⁄2:1 3-31⁄2:1
7⁄8 in. (22 mm)
vermiculite gypsum
plaster on metal lath
4
Notes:
1. New applications may be illegal in some jurisdictions.
2. Poured monolithically with concrete beams.

Table 16. Fire Resistance of Composite Floors (cont’d.)
Construction Floor
Plaster Mix
Ceiling
Fire
Resistance,
hr
Base
Coat
Finish
Coat
thick
21⁄2 in. (64 mm)
sand and
limestone
concrete
– –
17⁄8 in. (48 mm)
sprayed asbestos fiber1
and 31⁄8 in. (79 mm)
thickness around beam
4
21⁄2 in. (64 mm)
gravel concrete
– –
3⁄4 in. (19 mm) sprayed
asbestos fiber1
and 21⁄2
in. (64 mm) thickness
around beam
3
21⁄2 in. (64 mm)
gravel concrete
– –
gypsum plaster
2
Concrete on corrugated steel 31⁄4 in. (83 mm)
sand and gravel
concrete
2:1 3:1
1 in. (25 mm) gypsum
vermiculite plaster on
metal lath
4
4 in. (102 mm)
limestone air
entrained
concrete with
reinforced
concrete beams2
– – None 2
31⁄4 in. (83 mm)
sand and
limestone
concrete. Beam
either reinforced
concrete2
or
steel with 1 in.
(25 mm) fibered
gypsum
– – None 1
2 in. (51 mm)
gravel concrete
– –
3⁄4 in. (19 mm) perlite or
metal lath
2
2 in. 951 mm)
gravel concrete
– –
7⁄8 in. (22 mm) perlite or
metal lath
3
Concrete on corrugated steel
31⁄4 in. (83 mm)
expanded slag
concrete with
negative moment
reinforcement
2:1 –
3⁄8 in. (10 mm) gypsum
perlite plaster on metal
lath with 11⁄2 in. (38
mm) perlite plaster on
metal lath protection for
beam
4
31⁄4 in. (83 mm)
sand and
limestone
concrete
– –
asbestos fiber1
with
21⁄2 in. (64 mm)
thickness of same
material on beam
3
Reinforced concrete on concrete block
4 in. (102 mm)
lightweight
aggregate
concrete block
with 21⁄2 in. (64
mm) concrete
slab
– – None 3
Notes:
1. New applications may be illegal in some jurisdictions.
2. Poured monolithically with concrete beams.

FMDS0121 Fire Resistance Of Building Assemblies.pdf

FMDS0121 Fire Resistance Of Building Assemblies.pdf

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